There have been used expendables in various image forming systems such as a stencil printer, an ink jet recording system and the like for the reason of easiness in handling or the like. For example, in the stencil printer, an expendable such as a removable ink container or a stencil material roll is employed for the reason of easiness in handling or the like. The above-mentioned expendables are generally installed on the system body and are removed when the ink or the stencil material is exhausted after the ink or the stencil material is supplied to be discarded or to recycled. When a new expendable is mounted on the stencil printer, it is possible to continuously make print.
In Japanese Unexamined Patent Publication No. 2001-18507, there is proposed a method where, when forming an image by the use of such expendables, residue data is stored according to the residue of the expendable in, for instance, a memory IC provided on the expendable and the residue data is read out from the memory IC so that the residue of the expendable is displayed.
Further, in Japanese Unexamined Patent Publication No. 2003-7815, there is proposed a method where, when a stencil material roll is used as expendables for a stencil printer, residue data is stored in a memory IC as in the above-mentioned method, the residue data is read out when a stencil is to be made, and the rotational speed of a platen roller for conveying the stencil is controlled to be according to the residue data. The reason why the rotational speed of the platen roller is controlled according to the residue data is that though, when the stencil is conveyed, a tension is provided to the stencil in a direction reverse to the direction of conveyance so that the stencil is not wrinkled, the stencil material roll is gradually reduced in its diameter as the stencil material roll is consumed, and the tension on the stencil is increased therewith, whereby slip occurs between the platen roller and the stencil and the image on the stencil can be distorted. Accordingly, it is necessary to increase the rotational speed of the platen roller as the diameter of the stencil material roll reduces or the residue data reduces.
Further, in Japanese Unexamined Patent Publication No. 2003-4310, there is proposed a method where residue data of the stencil material roll is stored in a memory IC provided on the stencil material roll as in the above-mentioned method, the residue data is read out, and the operation of a thermal head is controlled with an amount of energy according to the residue data. The reason why the amount of energy of the thermal head is controlled according to the residue data is that since the surface smoothness deteriorates toward the center of the stencil material roll due to, for instance, a winding pressure when the stencil material is rolled into a roll and when the surface smoothness deteriorates, the contact of the stencil material with the thermal head fluctuates. Accordingly, it is necessary to increase the amount of energy of the thermal head as the distance to the center of the stencil material roll reduces or the residue data reduces.
However, in the image forming system where, for instance, the residue of the expendable is displayed on the basis of the residue data stored in a memory IC as described above, though, the preceding residue data is overwritten so that the new residue data is always recorded, a wrong residue can be displayed so that the operation of the platen roller or the thermal head cannot be adequately controlled if, for instance, the power source of the system body is turned off or noise is mixed when the residue data is to be recorded and residue data cannot be correctly recorded in the memory IC.
In view of the foregoing observations and description, the primary object of the present invention is to provide an image forming method, an image forming system and an expendable which permit, in those where the residue of an expendable is displayed or operation of the platen roller or the thermal head is controlled on the basis of residue data recorded in a memory IC as described above, adequate control of the part of the system even if the power source of the system body is turned off or noise is mixed when the residue data is to be recorded in the memory IC and residue data cannot be correctly recorded in the memory IC.